Fly.io

Fly.io has a native integration with Upstash where the databases are hosted in Fly. You can still access a Redis from Fly to Upstash but for the best latency, we recommend creating Redis (Upstash) inside Fly platform. Check here for details.

In this tutorial, we’ll walk you through the process of deploying a Redis by Upstash and connecting it to an application hosted on Fly.io. We’ll be using Node.js and Express for our example application, but the process can be easily adapted to other languages and frameworks.

Redis Setup

Create a Redis database using Fly CLI

> flyctl redis create
? Select Organization: upstash (upstash)
? Choose a Redis database name (leave blank to generate one):
? Choose a primary region (can't be changed later) San Jose, California (US) (sjc)

Upstash Redis can evict objects when memory is full. This is useful when caching in Redis. This setting can be changed later.
Learn more at https://fly.io/docs/reference/redis/#memory-limits-and-object-eviction-policies
? Would you like to enable eviction? No
? Optionally, choose one or more replica regions (can be changed later):
? Select an Upstash Redis plan 3G: 3 GB Max Data Size

Your Upstash Redis database silent-tree-6201 is ready.
Apps in the upstash org can connect to at redis://default:[e-mail]
If you have redis-cli installed, use fly redis connect to connect to your database.

Set up the Node.js application

• Create a new folder for your project and navigate to it in the terminal.
• Run npm init -y to create a package.json file.
• Install Express and the Redis client: npm install express redis
• Create an index.js file in the project folder with the following content:

const express = require("express");
const redis = require("redis");
const { promisify } = require("util");

const app = express();
const client = redis.createClient(process.env.REDIS_URL);

const getAsync = promisify(client.get).bind(client);
const setAsync = promisify(client.set).bind(client);

app.get("/", async (req, res) => {
  const value = await getAsync("counter");
  await setAsync("counter", parseInt(value || 0) + 1);
  res.send(`Hello, visitor number ${value || 0}!`);
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

This code creates a simple Express server that increments a counter in Redis and returns the visitor number.

Configure the Fly.io application

• Run fly init "your-app-name" to initialize a new Fly.io application.
• Choose the “Node.js (14.x)” builder, and accept the defaults for the remaining prompts.
• Open the fly.toml file that was generated and add the following environment variable under the [[services]] section:

[env]
  REDIS_URL = "<your-upstash-redis-url>"

Replace your-upstash-redis-url with the Redis URL from your Upstash instance.

Deploy the application to Fly.io

• Run fly deploy to build and deploy your application.
• After the deployment is complete, run fly status to check if the application is running.
• Visit the URL provided in the output (e.g., https://your-app-name.fly.dev) to test your application.

Conclusion

You have successfully deployed a Node.js application on Fly.io that uses an Upstash Redis instance as its data store. You can now build and scale your application as needed, leveraging the benefits of both Fly.io and Upstash.